Wheel assembly equipped with a tachometer

ABSTRACT

The equipment for measuring the speed of rotation of a vehicle wheel ( 14 ) carried by a wheel axle ( 12 ) comprises a tachometer ( 30 ) having a stator ( 32 ) suitable for being secured to the wheel axle ( 12 ), a rotor ( 34 ) suitable for being rotated by the wheel ( 14 ), and a connector ( 110 ) secured to the stator ( 32 ) for electrical connection of the tachometer. The connector ( 110 ) includes a set of connection terminals ( 114 A). The equipment further comprises an information transmission member ( 82 ) carried by the tachometer stator ( 32 ) and suitable for co-operating with a complementary information transmission member ( 74 ) constrained to rotate with the wheel ( 14 ). Said tachometer connector ( 110 ) includes additional connection terminals ( 114 B) to which said information transmission member ( 82 ) is connected for transmitting said information.

BACKGROUND OF THE INVENTION

The present invention relates to equipment for measuring the speed ofrotation of a vehicle wheel carried by a wheel axle, the equipment beingof the type comprising a tachometer having a stator suitable for beingsecured to the wheel axle, a rotor suitable for being rotated by thewheel, and a connector secured to the stator for electrical connectionof the tachometer, which connector includes a set of connectionterminals, the equipment further comprising an information transmissionmember carried by the stator of the tachometer and suitable forco-operating with a complementary information transmission memberconstrained to rotate with the wheel.

The invention also relates to a wheel assembly.

In airplanes, it is known to provide in each wheel axle with atachometer enabling the speed of rotation of the airplane wheel to bedetermined, in particular while running on the takeoff runway.

In addition, it is known to provide the wheels with devices fordetecting tire pressure. Such devices need to be associated with meansfor transmitting information between the wheel and the hub on which thewheel is rotatably mounted.

Those information transmission means generally comprise twocomplementary transmitter and receiver members disposed facing eachother. One is secured to the cover plate of the wheel substantially onthe axis of rotation, and the other is secured to the wheel axle, in thevicinity of the axis of rotation of the wheel.

Thus, one of the information transmission members is disposed inside thewheel axle in the vicinity of the tachometer.

Both the tachometer and the information transmission member secured tothe wheel axle have respective connectors enabling them to be wired to acable bundle leading to the airplane cockpit.

In certain types of airplane, in particular business airplanes, thespace available inside the axle for the tachometer and the informationtransmission member is very small.

Thus, in order to enable the cable bundle to be connected to bothconnectors, the connectors need to be placed in succession along theaxis of the axle. One of the connectors is then carried at the end of asupport arm secured to the tachometer. This arm is relatively long. Itis therefore fragile and constitutes a source of vibration.

SUMMARY OF THE INVENTION

An object of the invention is to propose a tachometer and an informationtransmission member that can easily be installed in a hub and that arecompact.

To this end, the invention provides equipment of the above-specifiedtype for measuring the angular speed of rotation of a wheel, theequipment being characterized in that said tachometer connector includesadditional connection terminals to which said information transmissionmember is connected to transmit said information.

In particular embodiments, the equipment further includes one or more ofthe following characteristics:

-   -   the information transmission member is secured to the tachometer        to form a unitary module, and it includes means for fixing the        unitary module to the wheel axle;    -   said means for fixing the unitary module to the wheel axle        comprise a bell adapted to be engaged in the wheel axle, and the        tachometer and the information transmission member are connected        to said bell;    -   the tachometer stator includes at least one duct for passing        conductors to provide the connection between the information        transmission member and the connection terminals of the        connector; and    -   the equipment has fitted thereto a shielded tube providing        mechanical and electromechanical protection to conductors        providing the connection between the information transmission        member and the connection terminals of the connector, which tube        extends generally along the stator.

The invention also provides a wheel assembly comprising a vehicle wheel,a wheel axle carrying the wheel, and equipment for measuring the speedof rotation of the wheel as defined above.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood on reading the followingdescription given purely by way of example and made with reference tothe drawings, in which:

FIG. 1 is a longitudinal section view of a wheel assembly of theinvention, the tire not being shown;

FIG. 2 is a view on a larger scale of the speed measuring equipmentshown on its own; and

FIG. 3 is a longitudinal section view of the tachometer shown on itsown.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The wheel assembly 10 shown in FIG. 1 forms part of the landing gear ofan airplane. It includes a landing gear axle 12 constituting astationary portion and a wheel 14 mounted to rotate about the axis X—Xof the axle.

The axle 12 presents a hollow body 16 of generally tubular shape aboutthe axis X—X. The body 16 is connected at one end 18 to the remainder ofthe structure of the landing gear. The other end, referenced 20, of thebody 16 forms a free end of the axle.

The wheel 14 is mounted to rotate about the axle 12 via two ballbearings 22 that are spaced about along the axis of the axle.

The wheel 14 comprises a rim 23 on which there is mounted a tire (notshown). The rim 23 comprises a hub 24 with a through passage 25 in whichthe axle 12 and the two ball bearings 22 are received.

The rim 23 also comprises an outer ring 26 for supporting a tire. Thehub 24 and the ring 26 are interconnected by radial arms 28 that areseparated from one another by ventilation slots.

Inside the axle 12 there is a tachometer 30 for measuring rotation ofthe wheel. The tachometer comprises a stator 32 secured to the axle 12and a rotor 34 that is rotatable relative to the stator.

The moving rotor is constrained to rotate with the wheel 14, e.g. bymeans of a cup 40 forming a cap fitted to the rim 23 on its axis. Thecup 40 presents an end wall 42 surrounded by a generally cylindricalside wall 44. At its open end, the side wall presents anoutwardly-directed peripheral collar 46 enabling the cup 40 to besecured to the rim 23, by means of screws 48.

The axis of the cup 40 extends generally along the axis of rotation X—Xof the wheel. The cup 40 includes an axial bushing 50 facing towards theaxle. This bushing presents a hole 52 suitable for receiving a shaft 54extending along the axis X—X. The shaft 54 is constrained to rotate withthe rotor 34 of the tachometer.

A resilient sleeve 55 placed in the hole 52 is interposed between thebushing 50 and the shaft 54. The sleeve 55 serves to drive the shaft 54in rotation from the bushing 50, while also accommodating any possibleaxial offsets. The connections between the sleeve 55 and the bushing 50,and between the sleeve 55 and the shaft 54 are provided by friction.

A pressure sensor 60 is mounted on the wheel. For this purpose, and inknown manner, the ring 26 of the wheel is provided with a housing 62 inwhich a pressure probe 64 is received that is suitable for measuring thepressure inside the tire on the wheel. The sensor 60 also includes asignal processor and probe control module 66. This module is connectedto the probe 64.

The module 66 is constituted by a printed circuit secured to the endwall of the cup 40 around the bushing 50.

A data processor unit 68 is secured to the stationary portion of thelanding gear or to the body of the airplane. It is adapted to make useof the pressure measurements taken by the sensor 60, and in particularto display them.

The sensor 60 and the data processor unit 68 are connected together byinformation communication means given overall reference 70. Thesecommunication means are adapted to establish transmission between thesensor 60 and the data processor unit 68, e.g. by radio. Thistransmission is both-way transmission, i.e. each entity can both sendand receive information.

These communication means are also adapted to transmit, by radio waves,the electrical energy needed to operate the sensor 60.

More precisely, the communication means 70 comprise a rotary coil 74secured to the wheel. This coil is carried by the cup 40 and is disposedon the axis X—X about the bushing 50.

In analogous manner, the communication means 70 include a stationarycoil 78 constrained in rotation with the axle 12.

The coils 74 and 78 are placed to face each other so as to establishradio wave communication between the moving and stationary portions ofthe wheel assembly.

The stationary coil 78 is carried by a support sleeve 80 engaged aroundthe shaft 54. The sleeve 80 is constrained in rotation with the body 32of the tachometer. The shaft 54 is free to turn through the sleeve 80.

The sleeve 80 and the stationary coil 78 together form an informationtransmission member 82 secured to the axle 12 and disposed inside it.The tachometer 30 and the information transmission member 82 are bothcarried by the same support bell 84 that connects them to the axle 12.

More precisely, and as shown in FIG. 2, the stator of the tachometer 30presents a body 90 of generally cylindrical shape having the rotor 34rotatably mounted therein. The rotor is extended by the shaft 54 beyonda front end of the body 90. At its rear end remote from the end wherethe rotor 34 is connected to the shaft 54, the body 90 is closed by anend cover 94. The body 90 is secured to the support bell 84 via itsfront end.

The bell 84 presents a flat end wall 102 with a passage formed throughthe center thereof for the shaft 54. The end wall 102 is surrounded by aperipheral cylindrical skirt 104 whose outside diameter corresponds tothe inside diameter of the axle 12.

The communication member 86 constituted by the sleeve 80 and thestationary coil 78 is disposed inside the bell 84 and is held to the endwall thereof, e.g. by means of screws 106 engaged through a collar 108formed integrally with the sleeve. These screws pass through the endwall 102 of the bell and are received in tapped blind holes 109 of thebody.

The tachometer 30 includes a connector 110 secured by screws 111 to therear cover 94. The connector 110 comprises a body 112 and a set ofconnection terminals 114 carried by the body. The connector is adaptedto establish an electrical connection with a connection cable 118 fittedat its end with a complementary connector 120 suitable for co-operatingwith the connector 110 and adapted to connect each terminal 114 thereofto independent conductor wires of the cable 118.

Some of the terminals 114A of the connector are connected to functionaldetector elements of the tachometer 30.

Other terminals 114B of the connector are connected by conductor wires122 to the stationary coil 78 of the information transmission member.These wires 122 pass through the body 90 and the cover 94 via a duct 124opening out behind the connector 110. The duct 124 is extended by ashielded tube 128 extending partially through the body 90 and partiallyalong it. The tube 128 extends essentially along the stator 32 of thetachometer. It terminates at an open end passing through an orifice 130formed in the end wall 102 of the bell so as to allow the wires 122 topass into the bell.

The tube is preferably made of metal so as to provide mechanical andelectromagnetic protection. It may also be made of an insulatingmaterial that is mechanically strong and that is covered in a layer ofmetallization.

Since the tube 128 is shielded and grounded, it provides electromagneticprotection for the signals coming from and going to the informationtransmission member 82 against the signal generated by the tachometer,thus ensuring that the tachometer signals and the signals of theinformation transmission member 82 are unaffected by one another.

Thus, the functional elements both of the tachometer 30 and of theinformation transmission member 82 are connected by electricalconductors to terminals 114 of a single connector 110.

Under such conditions, it will be understood that the speed measuringequipment constituted by the tachometer 30, and the informationtransmission member 82 together with its bell 84 can be mounted simplyas a single part inside the wheel axle 12, and that this equipment caneasily be connected by installing only one additional connector 120which is fitted to the connector 110.

In addition, as shown in FIG. 3, the tachometer 30 can, withoutmodification, be used in a wheel arrangement that does not includeinformation transmission means for transmitting pressure information.

Under such circumstances, the tachometer 30 is secured to the supportbell 84, but the information transmission member 82 is not secured tothe bell. In addition, the tube 128 is absent and the duct 124 is closedby a plug 140. The same connector 110 is retained. Nevertheless, theterminals 114B are not connected to conductor wires, and these terminalsmay even be omitted.

It can thus be seen that the same tachometer can be used in mostcontexts, with or without an associated information transmission member.This reduces the unit manufacturing cost of the tachometer, given largeproduction volume.

1. Equipment for measuring the speed of rotation of a vehicle wheel (14)carried by a wheel axle (12), the equipment comprising a tachometer (30)having a stator (32) suitable for being secured to the wheel axle (12),a rotor (34) suitable for being rotated by the wheel (14), and aconnector (110) secured to the stator (32) for electrical connection ofthe tachometer, which connector (110) includes a set of connectionterminals (114A), the equipment further comprising an informationtransmission member (82) carried by the stator (32) of the tachometerand suitable for co-operating with a complementary informationtransmission member (74) constrained to rotate with the wheel (14),wherein said tachometer connector (110) includes additional connectionterminals (114B) to which said information transmission member (82) isconnected to transmit said information, the tachometer providing a firstinformation and the information transmission member providing a secondinformation different from the first information.
 2. Measuring equipmentaccording to claim 1 wherein the information transmission member (82) issecured to the tachometer (30) to form a unitary module, and wherein theequipment includes means (84, 105) for fixing the unitary module to thewheel axle (12).
 3. Measuring equipment according to claim 2 whereinsaid means for fixing the unitary module to the wheel axle comprise abell (84) adapted to be engaged in the wheel axle (12), and wherein thetachometer (30) and the information transmission member (82) areconnected to said bell.
 4. Equipment according to claim 1 wherein thetachometer stator includes at least one duct (124) for passingconductors (122) to provide the connection between the informationtransmission member (82) and the connection terminals (114B) of theconnector (110).
 5. Equipment according to claim 1 the equipment havingfitted thereto a shielded tube (128) providing mechanical andelectromechanical protection to conductors (122) providing theconnection between the information transmission member (82) and theconnection terminals (114B) of the connector, which tube extendsgenerally along the stator (32).
 6. A wheel assembly comprising avehicle wheel (14), a wheel axle (12) carrying the wheel (14), andequipment for measuring the speed of rotation of the wheel according toclaim
 1. 7. Equipment of claim 1 wherein the tachometer provides speedinformation and the information transmission member provides non-speedinformation.
 8. Equipment for measuring the speed of rotation of avehicle wheel (14), comprising: a wheel assembly (10) including an axle(12), the axle comprising a hollow body (16) of tubular shape and a freeend (20); a wheel (14) mounted to rotate about an axis (X—X) of theaxle; a tachometer (30), mounted proximate the axle (12) measuringrotation of the wheel (14), comprising a stator (32) secured to the axle(12) and a rotor (34) rotatable relative to the stator, the moving rotorconstrained to rotate with the wheel (14); an information transmissionmember (82) carried by the stator (32) and co-operating with acomplementary information transmission member (74) constrained to rotatewith the wheel (14); and an electrical connector (110) secured to thestator (32), the connector (110) including a first set of connectionterminals (114A) and a second set of connection terminals (114B) thetachometer electrically connected to the first set of terminals (114A)to transmit an output of the tachometer, the information transmissionmember (82) connected to the second set of terminals (114B) to transmitan output of the information transmission member, the tachometerproviding a first information and the information transmission memberproviding a second information different from the first information. 9.Equipment of claim 8, wherein the tachometer provides speed informationand the information transmission member provides non-speed information.10. Equipment of claim 9, wherein the information transmission membertransmits a pressure value from a pressure sensor (60) mounted on thewheel.
 11. Equipment of claim 10 further comprising: a communicationcomponent (70) connected to the information transmission member; and anantenna connected to the communication component, the antenna receivingthe second information from a remote sensor.
 12. Equipment of claim 11wherein, the communication equipment (70) comprise a rotary coil (74)secured to the wheel and a stationary coil (78) constrained in rotationwith the axle (12), the rotary coil and the stationary coil placed toface each other so as to establish radio wave communication between themoving and stationary portions of the wheel assembly to transmit thepressure value from the pressure sensor to the information transmissionmember.
 13. Equipment of claim 12 wherein, a shaft (54) extends alongthe axis (X—X) of the axle, the shaft constrained to rotate with therotor of the tachometer, the stationary coil (78) is carried by asupport sleeve (80) engaged around the shaft, the sleeve (80)constrained in rotation with the stator (32) of the tachometer, theshaft (54) free to turn through the sleeve 80, the informationtransmission member being comprised of the sleeve (80) and thestationary coil (78) secured to the axle (12) and disposed inside theaxle.
 14. Equipment of claim 13, further comprising: a support bell (84)commonly carrying the tachometer (30) and the information transmissionmember (82) and connecting the tachometer and the informationtransmission member to the axle (12).
 15. Equipment for measuring thespeed of rotation of a vehicle wheel (14), comprising: an axle (12), theaxle comprising a hollow body (16) of tubular shape; a wheel (14)mounted to rotate about an axis (X—X) of the axle; a tachometer (30),mounted proximate the axle (12) measuring rotation of the wheel (14),comprising a stator (32) secured to the axle (12) and a rotor (34)rotatable relative to the stator, the moving rotor constrained to rotatewith the wheel (14), the tachometer outputting a speed signal; aninformation transmission member (82) carried by the stator (32) andco-operating with a complementary information transmission member (74)constrained to rotate with the wheel (14), the information transmissionmember outputting a non-speed signal; and an electrical connector (110)secured to the stator (32), the connector (110) including a first set ofconnection terminals (114A) and a second set of connection terminals(114B), the tachometer electrically connected to the first set ofterminals (114A) to transmit the speed output of the tachometer, theinformation transmission member (82) connected to the second set ofterminals (114B) to transmit the non-speed output of the informationtransmission member.
 16. The equipment of claim 15 wherein the non-speedoutput of the information transmission member is a tire pressure signal.17. The equipment of claim 15 wherein speed measuring elements of thetachometer (30) and the information transmission member (82) are mountedas a single part inside the hollow body of the axle.